1. Field of the Invention
The present invention relates, in general, to lancing elements for use in drawing bodily fluids out of a patient and, more particularly, to an improved lancing element including first and second elements positioned relative to each other such that an incision formed by the first element is held open by the second element and bodily fluids are pulled up the lancing element by surface tension on the first and second lancing elements.
2. Description of the Related Art
Integrated skin lancing and bodily fluid analysis samplers are known in the art. One such system is described and illustrated in WO 02/49507. The integrated system described in WO 02/49507 includes a lancing element or lance, which is attached to or integrated with a sensor strip adapted to measure the quantity of an analyte in bodily fluid or, alternatively, some characteristic of the bodily fluid. Usable bodily fluids may include, for example, blood or interstitial fluid (ISF). The lancing element is used to make an incision in the skin and the bodily fluid is drawn up the lancing element to the sensor strip by, for example, capillary action. Such integrated samplers may be combined with, for example, an electrochemical meter and referred to as monolithic or in-situ sampling devices.
Many lancing devices have been devised to form incisions and to enable bodily fluids to be withdrawn from those incisions. Solid lancets are used to open an incision in the skin to allow bodily fluids to escape to the surface of the skin where they can be sampled by the patient or the doctor. In order to ensure that enough fluid is released from the incision, such solid lancing elements are generally larger in diameter to facilitate the flow of sufficient bodily fluids from the incision for sampling purposes. However, such solid needles generally rely on the size of the incision to ensure that enough bodily fluids are expressed and are not used to facilitate the flow of fluids to the testing apparatus.
Hollow needles have also been described for use in drawing fluids out of the body for testing purposes; such needles may have a pointed or beveled end to facilitate opening the incision. In such needles, the incision is held open by the outer diameter of the needle to facilitate the flow of bodily fluids out of the incision and the bodily fluids are drawn up the needle either by a vacuum or by capillary action or by a combination of vacuum and capillary action.
Other lancing devices have been described wherein the lance is a flat or partially curved piece which includes an open channel for guiding fluid from the sharpened tip to the proximal end of the lance by means of, for example, surface tension and/or capillary action. Such lancing elements are advantageous because of the ease of manufacture and the ease of integrating them into, for example, a sensor strip, in order to facilitate both lancing and measurement in a single element. Where the landing element is a flat or partially flat piece which includes an open channel for guiding fluid, it is possible for the edges of the incision to close on the channel, fully or partially blocking the channel and preventing bodily fluids from flowing to the proximal end of the channel or limiting the amount of fluid which can flow.
Problem to be Solved
It would, therefore, be advantageous to design a lancing device where the lancing element is a flat or partially curved piece including an open channel and the lancing element includes a separation element for holding the incision open when the lancing element is in the wound and preventing the edges of the incision from closing on the lancing element and partially or fully blocking the open channel. It would be advantageous to design a lancing device wherein the separation element is positioned slightly proximal to the sharpened tip of the lancing element to facilitate insertion of the lance into the skin. It would further be advantageous to design a lancing device wherein the lancing element and the separation element are formed from a single metal sheet. It would further be advantageous to design a lancing device wherein the lancing element and the separation element are positioned opposite each other such that fluid is pulled up the lancing element and into the open channel by surface tension between the fluid and the lancing element and separation element, thus facilitating the filling of the channel. It would further be advantageous to design a lancing device wherein the lancing element and the separation element are formed from a single sheet of metal rolled to position the separation element opposite the lancing element such that the proximal end of the lancing element and the separation element form an open channel. It would further be advantageous to manufacture the lancing devices described herein using, for example, a metal forming or stamping process.